The present invention relates to a formwork apparatus used for concrete placing in the constructing of concrete structures such as dams.
Heretofore, sliding forms are used for concrete placing when concrete structures, for example the concrete walls of dams, are built. These sliding forms have form panels which can slide upwards and downwards. Concrete is poured and placed inside these panels. After the concrete is cured, the panels are released from the cured concrete wall and slide upward to replace themselves. In order to release one of the form panels from the concrete wall, two or three workers get on a scaffold attached to the sliding form and sling the panel. Thereafter, they loosen fixing bolts used for fixing the sliding form to the wall, and then come off the scaffold temporarily. Then, a crane hangs up the form panel in order to slide it upwards. After the panel is raised to the position, the workers get on the scaffold again and fix the sliding form, which is still hung by the crane, to the cured concrete wall with the fixing bolts. Again, concrete is then poured inside the form panel, and subsequent operations are continued in the same manner.
As described above, the sliding forms require manual labor and such large scale equipment as a crane for replacement of the form panel, thereby causing the cost of the concrete placing to increase. Moreover, the panel replacement operation is performed in a low safety, low efficiency environment since it must be done at a high altitude on the scaffold. Furthermore, it is impossible to construct a curved concrete wall with the sliding forms because of the difficulty in sliding the panels in curved manner.